A known heat exchanger (disclosed in German Patent 2 818 892) includes a base that consists of a thicker tube sheet that the gas-conveying pipes extend through loosely, leaving annular gaps, and of a thinner tube sheet that the gas-conveying pipes are welded into. The thinner tube sheet is secured at its outer circumference to the thicker tube sheet and rests on it by way of the gas-conveying pipes. The line that supplies the coolant empties between the two tube sheets and the coolant enters the heat exchanger through the annular gaps. Aside from the exploitation of the gas-conveying and hence pressurized pipes to secure the thinner tube sheet, the known heat exchanger entails the drawback that any particles suspended in the coolant, water, will precipitate on the inner surface of the thinner tube sheet, where it can cause overheating.
Also known (from Austrian Patent 361 953) is an upright heat exchanger with a sheaf of pipes secured in two tube sheets. The upper tube sheet, the tube sheet at the outgoing-gas end, is provided with cooling channels that communicate with the inside of the heat exchanger through the gaps around the gas-conveying pipes.
The object of the present invention is to improve the generic heat exchanger to the extent that the tube sheet at the gas-end has thinner walls and that the coolant will flow through it without leaving deposits of solid particles on its coolant-end surface.
The tube sheet in the heat exchanger in accordance with the present invention can in general be thick enough to withstand the high pressure exerted by the coolant. The cooling channels that extend through the tube sheet can be distributed to allow the walls between the heat-emitting reaction gas and the pressurized and heat-absorbing coolant, boiling water, to remain thin. The coolant will flow rapidly enough through the cooling channels to prevent any suspended solid particles from depositing on the coolant side of the tube sheet and to rinse them away. Since the tube sheet is above the lower edge of the jacket, the solid particles will be able to accumulate below the tube sheet, at the lowest point of the heat exchanger. This lowest point can, in one version of the invention, remain unheated. If the supply of coolant is interrupted and the flow of gas turned off, enough coolant will flow through the channels that are exposed to the jacket to initiate emergency cooling and remove the residual heat.
The alternating obstruction of the ends of the channels will produce mutually opposed coolant flows in the adjacent channels. The result will be a rotary current in the annular gaps around the gas-conveying pipes that will thoroughly cool that vicinity.